- Implemented.

Safari/iPhone recording now uses MP4/AAC when WebM is unavailable.
WebM remains the default when supported and FFmpeg is disabled.
Added optional FFmpeg profiles: recommended M4A/AAC-LC or requested 
MP4/H.264 + AAC.
Added MIME-aware, playsinline audio playback.
Added dashboard controls under Plans & Platform → Voice Transcoding / 
FFmpeg.
Added Apache/Nginx media MIME configuration and documentation.
Core implementation: voice_transcoder.php (line 72), messages.php (line 
86), and cyberchat-app.js (line 635).

config.json

@@ -24,7 +24,15 @@
     "max_duration_seconds": 60,
     "max_upload_bytes": 12582912,
     "auto_play_default": true,
-    "upload_dir": "uploads/voice"
+    "upload_dir": "uploads/voice",
+    "transcoding": {
+      "enabled": false,
+      "ffmpeg_path": "ffmpeg",
+      "profile": "m4a_aac",
+      "audio_bitrate_kbps": 128,
+      "timeout_seconds": 45,
+      "fallback_to_source": true
+    }
   },
   "database": {
     "main_db": "db/chat.sqlite",